This invention relates to the use of a clipper to enclose material in bags, tubular casing, or netting and to control crimp. Clippers are conventionally used to enclose food products such as poultry in plastic bags, to enclose pasty sausage material in tubular casing, and to enclose sausages or hams in netting, as well as for numerous other applications. Clippers can be manual or automatic. Automatic clippers use powered cylinders, usually air-actuated, to provide a downstroke on a punch. Manual clippers generally use a lever to actuate the downstroke of the punch. In either type of clipper, the punch engages a clip, which is then forced around a gathered neck of the bag, easing, or netting, and against a die, which forces or “crimps” the legs of the clip closed to seal the hag, casing, or netting. A type of automated neater using a clipper is described in U.S. Pat. No. 6,883,297, Apparatus for Enclosing Material in a Net, the disclosure of which is incorporated herein by reference. Clips are described in U.S. Pat. No. 7,565,780, Clip and Clipper, the disclosure of which is incorporated herein by reference.
Precise control of crimp is necessary for optimum operation. The punch of the clipper must travel an appropriate distance to cause the clip to crimp properly. This distance varies with different types of clips, which might be different sizes. The distance also varies with differently-sized bags, casings, and nets, if the punch travels too short a distance, the clip is not crimped sufficiently tightly and will not properly enclose the bag, casing, or netting. The enclosed material then can escape the enclosure, resulting in unsanitary and unsavory conditions. Additionally, sometimes material is vacuum packed, as described in, for example, United States Published Patent Application No. 2011/0107726 A1, Method and System for Bagging Material, the disclosure of which is incorporated herein by reference. For example, it is known to enclose a whole bird in a plastic bag, evacuate the bag, and seal the bag with a clip. Vacuum packing of, for example, chicken, produces a tight appearance that is pleasing to consumers. A loose clip, however, will cause the bag to lose vacuum.
Moreover, if the distance the punch travels is too far, the clip is crimped too tightly, causing similar problems to arise. A clip crimped too tightly can cut the bag or casing, causing one or more of a leak of the contents, a loss of vacuum, and contamination of the material.
Accordingly, precise control of crimp is important when bagging material. The amount of adjustment needed might be very small, as small as four millimeters or less, but it is nevertheless critical to proper casing, bagging, and/or netting operation.
One prior-art method of crimp control uses a cam within the air-actuated cylinder. Modern air-actuated cylinders can use air actuation for both the downstroke and the return stroke. The cam arrangement, however, only permitted air actuation of the downstroke of the piston. Accordingly, a spring was used to cause the piston to rebound to the top of the cylinder.
Another prior-art method of crimp control uses screws to adjust the height of the die. The screws could stick or freeze, however, after extended periods of time, especially if not maintained well, causing difficulties when crimp had to be adjusted.
The present invention is an improved apparatus for control of crimp during clipping operations.